U.S. Pat. Nos. 7,314,849 and 7,300,907 describe respectively certain 6-(poly-substituted aryl)-4-aminopicolinate and 2-(poly-substituted aryl)-6-amino-4-pyrimidinecarboxylic acid compounds and their use as herbicides. 2-Fluoro-3-substituted-4-chlorophenylboronic acid derivatives are useful intermediates for the preparation of these herbicides.
In U.S. Pat. Nos. 7,314,849 and 7,300,907, for instance, 2-fluoro-3-substituted-4-chlorophenyl-boronic acids derivatives are prepared by halogen-metal exchange of 1-bromo-2-fluoro-3-substituted-4-chlorobenzenes with n-butyl lithium followed by quenching with a boronic acid ester.
It would be advantageous to produce these materials by direct deprotonation rather than by halogen-metal exchange. This allows the use, for instance, of less complex starting materials and avoids the formation of a brominated waste stream.